1. Field of the Invention
The present invention relates to a pressure gauge comprising a plate having a pointer mechanism and a bourdon-tube mounting plus connection arranged on one side thereof and a bezel arranged on on the opposite side thereof.
2. Prior Art
In such a pressure gauge, the pointer mechanism and the bourdon-tube mounting complete with the tube and connection, are attached to said surface of the disc-shaped supporting plate as by riveting. This baffle plate is rigidly fixed between the cup-shaped glass and the likewise cup-shaped cover, the connection between the glass and housing cover being effected by means of an adhesive. The cup-shaped housing cover exhibits an opening for the connection element of the bourdon tube mounting. The baffle plate is here designed at the same time as a bezel.
Such pressure gauges are encumbered with a number of drawbacks. One disadvantage is that the glass is not exchangeable something which is required in pressure gauges used in welding work. Because of the presence of the fixing element on the bourdon tube mounting and because of the lateral extension of the tube, the mounting plus connection is of relatively long length so that the costs of the materials for this component are relatively high. A major drawback is that there is no sealed connection between the opening in the housing cover and the bourdon tube mounting; this is not possible in fact. The space defined by the baffle plate and the cup-shaped housing cover, must be sealed however.
In such pressure gauges, however, there is the requirement for the housing cover to be provided with a blow-out hole which is normally closed off by a cover. The purpose of this is to ensure that in the event of a fault in the bourdon tube, the pressure developing inside the pressure gauge forces out the cover located at the back of the gauge. In this way, the pressure developed inside the gauge is collapsed without doing further damage to the gauge. The baffle plate is intended in the event of this kind of situation, to prevent the front of the gauge from being damaged,